SANTA MONICA, Calif. & BOTHELL, Wash.--(BUSINESS WIRE)--Agensys, Inc., an affiliate of Tokyo-based Astellas Pharma Inc., and Seattle Genetics, Inc. (Nasdaq:SGEN) today announced that they have initiated a phase I clinical trial of ASG-5ME for the treatment of castration-resistant prostate cancer. ASG-5ME is an antibody-drug conjugate (ADC) targeting the SLC44A4 antigen and is being co-developed by both companies for the treatment of solid tumors.